Talking About Pot with Cancer Patients

Discrepancy between oncologists' actions, knowledge

Cancer specialists frequently discussed medical marijuana with patients and almost half recommended cannabis for treatment, even though fewer than a third of the clinicians felt sufficiently informed, a national survey showed.

Overall, 80% of the 237 oncologists surveyed said they had discussed medical marijuana with patients, and 46% reported they had recommended medical marijuana for management of cancer-related issues. Almost 80% of the conversations were initiated by patients, as reported online in the Journal of Clinical Oncology (JCO).

Having expertise in medicine means "knowing what you know, as well as what you don't know," said Andrew Epstein, MD, of Memorial Sloan Kettering Cancer Center in New York City, who was not involved with the study. "In the case of an emerging potential treatment option like medical marijuana, it's understandable there might be some discrepancy in how much an oncologist knows about that option and how much they think that option might be beneficial or at least useful for consideration for a patient."

The study raises questions about the current evidence base for medical marijuana and points out a need for more research to evaluate the benefit-burden ratio for medical marijuana as compared with other treatments for cancer and cancer-related side effects, added Epstein, who is a clinical expert for the American Society of Clinical Oncology. A better understanding of the logistics surrounding medical marijuana also is needed.

"A state might have made it legal for medical marijuana to be dispensed, but an individual might not have the process in place to dispense it." Oncologists in states that have not legalized medical marijuana need education about the therapeutic alternatives that might be available, he added.

As of the JCO article's publication date, 30 states and the District of Columbia had legalized use of marijuana for medical purposes, and all but one of the laws included cancer as a qualifying condition. The authors noted that the state laws encompass a complex topic, including terminology, biology, and formulations.

The term "medical marijuana" refers to nonpharmaceutical cannabis products that healthcare providers may recommend for therapeutic purposes that comply with state law. On the other hand, "therapeutic marijuana" refers to nonpharmaceutical cannabis products used with "medicinal intent," regardless of compliance with the law.

Medical marijuana comes in a variety of strains and potencies, the authors continued. The products might be "smoked, vaporized, ingested, taken sublingually, or applied topically."

No randomized trials have evaluated medical marijuana for oncology indications. As a result, oncologists must extrapolate from research on pharmaceutical cannabinoids or from evidence involving patients with other diseases and conditions.

Oral synthetic tetrahydrocannabinol received FDA approval for treating chemotherapy-induced nausea and vomiting. However, cannabis has hundreds of active ingredients that have both synergistic and inhibitory "entourage effects," the authors noted, making comparisons between whole-plant medical marijuana and pharmaceutical cannabinoids that contain one or two ingredients. Observational studies showed that medical marijuana legalization is associated with reductions in opioid-related hospitalizations, but no randomized trials have compared the two strategies for pain relief.

Previous surveys of oncologist attitudes about medical marijuana addressed only use as an antiemetic and were conducted prior to passage of current laws. Braun and colleagues sought to obtain contemporary information about oncologists' views and knowledge about clinical use of medical marijuana.

The investigators mailed surveys to 400 randomly selected medical oncologists. The survey included questions about clinical discussions of marijuana, views on comparative efficacy versus other therapies, risks of medical marijuana versus other therapies, and items to allow comparisons of respondent characteristics and their answers.

79.8% of the oncologists discussed medical marijuana with patients or families

78% of the conversations were initiated by patients or families

45.9% of the oncologists recommended marijuana clinically

56.2% of those who recommended marijuana did not consider themselves sufficiently knowledgeable to make recommendations

29.4% of all respondents felt sufficiently knowledgeable to make recommendations about medical marijuana

The authors reported geographic variation in the responses: Oncologists in the South were least likely (69%) to report discussing medical marijuana with patients or families or recommending it (34.7%), and those practicing in the West were most likely (95%, 84%; P=0.02, P<0.001). Oncologists who had a high practice volume (>60 patients weekly) and who practiced outside a hospital were also more likely to report discussions about medical marijuana, and practicing outside a hospital increased the likelihood of recommending medical marijuana.

With regard to oncologists' perceptions about the effectiveness of medical marijuana, a third said they considered medical marijuana to be at least as effective or more effective than standard pain treatments, another third said it was less effective, and another third said they did not know. Two thirds of the respondents said medical marijuana is equivalent to or better than standard medications for cachexia. A minority said medical marijuana was at least equivalent to standard therapy for nausea and vomiting (48.4%), anxiety (45.8%), coping (40.3%), and poor sleep (34.9%).

The proportion of oncologists who responded "I don't know" regarding medical marijuana's effectiveness varied by indication, from 27.6% for poor appetite/cachexia to 45.1% for poor sleep.

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